Liquid crystal display devices have been used for watches and electronic calculators and in recent years for various applications including measuring devices, automobile meters, copying machines, cameras, display devices for office appliances and display devices for consumer products. Accordingly, various functions including a wide temperature range for operation, a low voltage for driving, a high response speed, a high contrast ratio, a wide visual angle and chemical stability, are required for such liquid display devices.
However, at present, there is no single material which by itself satisfies all of such requirements, and it is common to satisfy such requirements by a liquid crystal composition prepared by mixing a plurality of liquid crystal materials and non-liquid crystal materials. Accordingly, it is desired to develop a liquid crystal material or a non-liquid crystal material which is excellent in one or more functions, if not in all the required functions.
In the field of the display device using liquid crystal, it is desired to improve its performance. For this purpose, low voltage driving, highly fine display, a high contrast ratio, a wide visual angle characteristic, a low temperature response characteristic and a wide range of driving temperature are, for example, desired. These functions have a tendency such that when some of them are improved, others have to be sacrificed.
Recently, improvement of a response speed is particularly desired. For example, in driving the device by an electrical cell, low voltage drive and high speed response are desired; in e.g. the office appliances, highly fine display and high speed response are required; and in the display for automobiles, low temperature response or high speed response within a wide temperature range for operation is desired.
In this respect, several methods for improvement are conceivable. One of them is to adopt a liquid crystal composition having a low viscosity. Namely, if the viscosity of the liquid crystal composition is reduced, the response speed can be improved so that a display will be possible at a practical speed even at a low temperature. Further, if the response speed may be at a level equal to the conventional speed, it will be possible to drive the device at a lower voltage, or a higher duty drive or highly fine drive, will be possible.
For such a purpose, a p,p'-disubstituted difluorostilbene compound has been proposed, as disclosed at the 16th Liquid Crystal Discussion Meeting. This compound has a chemical structure as shown by the following formula (3): ##STR1## provided that in the formula (3), each of R.sup.A and R.sup.B is a n-alkyl group, a n-alkoxy group or a n-alkoxycarbonyl group.
The compound of this formula (3) has a low viscosity and has the stability against light improved over a stilbene compound which is not substituted by fluorine. However, as compared with commonly employed liquid crystal compounds, its stability against light is still poor, whereby in many cases, the useful environment has been rather limited, or it has been required to use an ultraviolet ray-preventive film.
Accordingly, a liquid crystal material having a low viscosity and having a high stability against light, has been desired.
It is an object of the present invention to provide a novel material thereby to solve the above problem.
The present invention provides a difluoro-derivative compound of the following formula (1): EQU R.sup.1 --(A.sup.1 --Y.sup.1).sub.m --A.sup.2 CF.dbd.CF--C.tbd.C--A.sup.3 --(Y.sup.2 --A.sup.4).sub.n --R.sup.2 ( 1)
provided that in the formula (1), A.sup.1, A.sup.2, A.sup.3, A.sup.4, Y.sup.1, Y.sup.2, m, n, R.sup.1 and R.sup.2 are as follows:
each of A.sup.1, A.sup.2, A.sup.3 and A.sup.4, which are independent from one another, is a cyclic group selected from a trans-1,4-cyclohexylene group, a 1,4-cyclohexenylene group and a 1,4-phenylene group, wherein each of such cyclic groups is unsubstituted or substituted by one or more halogen atoms or cyano groups, one or more .dbd.CH-- groups constituting rings of such cyclic groups may be substituted by nitrogen atoms, and one or more --CH.sub.2 -- groups constituting rings of such cyclic groups may be substituted by oxygen atoms or sulfur atoms;
each of Y.sup.1 and Y.sup.2, which are independent from each other, is --COO--, --OCO--, --C.tbd.C--, --CH.sub.2 CH.sub.2 --, --CH.dbd.CH--, --OCH.sub.2 --, --CH.sub.2 O-- or a single bond;
each of m and n, which are independent from each other, is 0 or 1; and
each of R.sup.1 and R.sup.2 which are independent from each other, is a C.sub.1-10 alkyl group, a halogen atom or a cyano group, provided that in the case of the alkyl group, an oxygen atom, a carbonyloxy group or an oxycarbonyl group may be interposed in a carbon-carbon bond of the alkyl group or in a carbon-carbon bond between this alkyl group and the adjacent cyclic group, some of carbon-carbon bonds in the alkyl group may be triple bonds or double bonds, one --CH.sub.2 -- group in the alkyl group may be substituted by a carbonyl group, and some or all of hydrogen atoms in the alkyl group may be substituted by fluorine atoms.
The present invention also provides a difluoro-derivative compound of the formula (2) R.sup.1 --A.sup.2 --CF.dbd.CF--C.tbd.C--A.sup.3 --R.sup.2 (wherein A.sup.2, A.sup.3, R.sup.1 and R.sup.2 are as defined with respect to the formula (1)), a compound having a liquid crystal property selected from such derivatives, and a liquid crystal composition containing a compound of the formula (1) or (2).
Further, the present invention provides a liquid crystal electro-optical device having a compound of the formula (1) or (2) interposed between substrates provided with electrodes.
The compound of the formula (1) of the present invention has a low viscosity, and it is excellent in compatibility with other liquid crystals or non-liquid crystals and is a material which is chemically stable particularly against light.
The following compounds may be mentioned to show the specific structures of the compound of the present invention. As a typical compound having two rings, the following compound may be mentioned. EQU R.sup.1 --A.sup.2 --CF.dbd.CF--C.tbd.C--A.sup.3 --R.sup.2 ( 4)
More specifically, the compound of the formula (4) includes the following compounds. In the following description, "--Ph--" represents a 1,4-phenylene group, "--Cy--" represents a trans-1,4-cyclohexylene group and "--Ch--" represents a 1,4-cyclohexenylene group. This applies not only to the compound of the formula (4) but also to other compounds. The cyclohexenylene group is preferably a 4-substituted 1-cyclohexenyl group. EQU R.sup.1 --Ph--CF.dbd.CF--C.tbd.C--Ph--R.sup.2 ( 4A) ##STR2##
The following compound may be mentioned as a compound of the formula (4A) wherein the 1,4-phenylene groups are replaced by trans-1,4-cyclohexylene groups; EQU R.sup.1 --Cy--CF.dbd.CF--C.tbd.C--Cy--R.sup.2 ( 4B) ##STR3##
Further, the following compound may be mentioned as a compound of the formula (4A) wherein the 1,4-phenylene groups are replaced by 1,4-cyclohexylene groups; EQU R.sup.1 --Ch--CF.dbd.CF--C.tbd.C--Ch--R.sup.2 ( 4C) ##STR4##
Further, the following compound may be mentioned as a compound of the formula (4A) wherein one of the 1,4-phenylene groups is replaced by a trans-1,4-cyclohexylene group; EQU R.sup.1 --Ph--CF.dbd.CF--C.tbd.C--Cy--R.sup.2 ( 4D) ##STR5##
Further, the following compound may be mentioned as a compound of the formula (4A) wherein one of the 1,4phenylene groups is replaced by a 1,4-cyclohexenylene group; EQU R.sup.1 --Ph--CF.dbd.CF--C.tbd.C--Ch--R.sup.2 ( 4E) ##STR6##
Further, the following compound may be mentioned as a compound of the formula (4A) wherein one of the 1,4-phenylene groups is replaced by a trans-1,4-cyclohexylene group and the other is replaced by a 1,4-cyclohexenylene group; EQU R.sup.1 --Cy--CF.dbd.CF--C.tbd.C--Ch--R.sup.2 ( 4F) ##STR7##
Further, the following compound may be mentioned as a compound of the formula (4A) wherein the 1,4-phenylene groups are phenylene groups with some of hydrogen atoms replaced by fluorine atoms. Here, "PhF" represents a monofluoro-1,4-phenylene group or a polyfluoro-1,4-phenylene group, provided that each of j and k which are independent from each other, is an integer of from 1 to 4. EQU R.sup.1 --PhF--CF.dbd.CF--C.tbd.C--PhF--R.sup.2 ( 4G) ##STR8##
Further, the following compounds may be mentioned as compounds having three rings: EQU R.sup.1 --A.sup.1 --A.sup.2 --CF.dbd.CF--C.tbd.C--A.sup.3 --R.sup.2( 5) EQU R.sup.1 --A.sup.2 --CF.dbd.CF--C.tbd.C--A.sup.3 --A.sup.4 --R.sup.2( 6)
More specifically, the following compounds may be mentioned as the compound of the formula (5): EQU R.sup.1 --Ph--Ph--CF.dbd.CF--C.tbd.C--Ph--R.sup.2 ( 5A) ##STR9## EQU R.sup.1 --Cy--Cy--CF.dbd.CF--C.tbd.C--Cy--R.sup.2 ( 5B) EQU R.sup.1 --Ch--Ch--CF.dbd.CF--C.tbd.C--Ch--R.sup.2 ( 5C) EQU R.sup.1 --Ph--Ph--CF.dbd.CF--C.tbd.C--Cy--R.sup.2 ( 5D) EQU R.sup.1 --Ph--Ph--CF.dbd.CF--C.tbd.C--Ch--R.sup.2 ( 5E) EQU R.sup.1 --Cy--Cy--CF.dbd.CF--C.tbd.C--Ph--R.sup.3 ( 5F) EQU R.sup.1 --Cy--Cy--CF.dbd.CF--C.tbd.C--Ch--R.sup.2 ( 5G) EQU R.sup.1 --Ch--Ch--CF.dbd.CF--C.tbd.C--Ph--R.sup.2 ( 5H) EQU R.sup.1 --Ch--Ch--CF.dbd.CF--C.tbd.C--Cy--R.sup.2 ( 5I) EQU R.sup.1 --Cy--Ph--CF.dbd.CF--C.tbd.C--Ph--R.sup.2 ( 5J) EQU R.sup.1 --Ph--Cy--CF.dbd.CF--C.tbd.C--Ph--R.sup.2 ( 5K) EQU R.sup.1 --Ph--Ch--CF.dbd.CF--C.tbd.C--Ph--R.sup.2 ( 5L) EQU R.sup.1 --Ch--Ph--CF.dbd.CF--C.tbd.C--Ph--R.sup.2 ( 5M) EQU R.sup.1 --Cy--Ch--CF.dbd.CF--C.tbd.C--Ph--R.sup.2 ( 5N) EQU R.sup.1 --CH--Cy--CF.dbd.CF--C.tbd.C--Ph--R.sup.2 ( 5O) EQU R.sup.1 --Ph--Cy--CF.dbd.CF--C.tbd.C--Cy--R.sup.2 ( 5P) EQU R.sup.1 --Cy--Ph--CF.dbd.CF--C.tbd.C--Cy--R.sup.2 ( 5Q) EQU R.sup.1 --Ph--Ch--CF.dbd.CF--C.tbd.C--Cy--R.sup.2 ( 5R) EQU R.sup.1 --CH--Ph--CF.dbd.CF--C.tbd.C--Cy--R.sup.2 ( 5S) EQU R.sup.1 --Cy--Ch--CF.dbd.CF--C.tbd.C--Cy--R.sup.2 ( 5T) EQU R.sup.1 --Ch--Cy--CF.dbd.CF--C.tbd.C--Cy--R.sup.2 ( 5U) EQU R.sup.1 --Ph--Cy--CF.dbd.CF--C.tbd.C--Ch--R.sup.2 ( 5V) EQU R.sup.1 --Cy--Ph--CF.dbd.CF--C.tbd.C--Ch--R.sup.2 ( 5W) EQU R.sup.1 --Ph--Ch--CF.dbd.CF--C.tbd.C--Ch--R.sup.2 ( 5X) EQU R.sup.1 --Ch--Ph--CF.dbd.CF--C.tbd.C--Ch--R.sup.2 ( 5Y) EQU R.sup.1 --Cy--Ch--CF.dbd.CF--C.tbd.C--Ch--R.sup.2 ( 5Z) EQU R.sup.1 --Ch--Cy--CF.dbd.CF--C.tbd.C--Ch--R.sup.2 ( 5a) EQU R.sup.1 --Ph--PhF--CF.dbd.CF--C.tbd.C--Ph--R.sup.2 ( 5b) EQU R.sup.1 --Cy--PhF--CF.dbd.CF--C.tbd.C--Ph--R.sup.2 ( 5c) EQU R.sup.1 --Ch--PhF--CF.dbd.CF--C.tbd.C--Ph--R.sup.2 ( 5d) EQU R.sup.1 --Ph--PhF--CF.dbd.CF--C.tbd.C--Cy--R.sup.2 ( 5e) EQU R.sup.1 --Cy--PhF--CF.dbd.CF--C.tbd.C--Cy--R.sup.2 ( 5f) EQU R.sup.1 --Ch--PhF--CF.dbd.CF--C.tbd.C--Cy--R.sup.2 ( 5g) EQU R.sup.1 --Ph--PhF--CF.dbd.CF--C.tbd.C--Ch--R.sup.2 ( 5h) EQU R.sup.1 --Cy--PhF--CF.dbd.CF--C.tbd.C--Ch--R.sup.2 ( 5i) EQU R.sup.1 --Ch--PhF--CF.dbd.CF--C.tbd.C--Ch--R.sup.2 ( 5j)
More specifically, the following compounds may be mentioned as the compound of the formula (6): EQU R.sup.1 --Ph--CF.dbd.CF--C.tbd.C--Ph--Ph--R.sup.2 ( 6A) ##STR10## EQU R.sup.1 --Cy--CF.dbd.CF--C.tbd.C--Cy--Cy--R.sup.2 ( 6B) EQU R.sup.1 --Ch--CF.dbd.CF--C.tbd.C--Ch--Ch--R.sup.2 ( 6C) EQU R.sup.1 --Cy--CF.dbd.CF--C.tbd.C--Ph--Ph--R.sup.2 ( 6D) EQU R.sup.1 --Ch--CF.dbd.CF--C.tbd.C--Ph--Ph--R.sup.2 ( 6E) EQU R.sup.1 --Ph--CF.dbd.CF--C.tbd.C--Cy--Cy--R.sup.2 ( 6F) EQU R.sup.1 --Ch--CF.dbd.CF--C.tbd.C--Cy--Cy--R.sup.2 ( 6G) EQU R.sup.1 --Ph--CF.dbd.CF--C.tbd.C--Ch--Ch--R.sup.2 ( 6H) EQU R.sup.1 --Cy--CF.dbd.CF--C.tbd.C--Ch--Ch--R.sup.2 ( 6I) EQU R.sup.1 --Ph--CF.dbd.CF--C.tbd.C--Ph--Cy--R.sup.2 ( 6J) EQU R.sup.1 --Ph--CF.dbd.CF--C.tbd.C--Ph--Ch--R.sup.2 ( 6K) EQU R.sup.1 --Ph--CF.dbd.CF--C.tbd.C--PhF--Ph--R.sup.2 ( 6L) EQU R.sup.1 --Ph--CF.dbd.CF--C.tbd.C--PhF--Cy--R.sup.2 ( 6M) EQU R.sup.1 --Ph--CF.dbd.CF--C.tbd.C--PhF--Ch--R.sup.2 ( 6N)
Furthermore, the following compounds may be mentioned as compounds having three rings wherein Y.sup.1 and Y.sup.2 between rings are changed to other than a single bond: EQU R.sup.1 --Ph--Ph--C.tbd.C--Ph--CF.dbd.CF--C.tbd.C--Ph--R.sup.2( 7A) EQU R.sup.1 --Ph--CH.sub.2 CH.sub.2 --Ph--CF.dbd.CF--C.tbd.C--Ph--R.sup.2( 7B) EQU R.sup.1 --Ph--OCH.sub.2 --Ph--CF.dbd.CF--C.tbd.C--Ph--R.sup.2( 7C) EQU R.sup.1 --Ph--CH.sub.2 O--Ph--CF.dbd.CF--C.tbd.C--Ph--R.sup.2( 7D) EQU R.sup.1 --Ph--COO--Ph--CF.dbd.CF--C.tbd.C--Ph--R.sup.2 ( 7E) EQU R.sup.1 --Ph--OCO --Ph--CF.dbd.CF--C.tbd.C--Ph--R.sup.2 ( 7F) EQU R.sup.1 --Ph--C.tbd.C--Ph--CF.dbd.CF--C.tbd.C--Ph--R.sup.2 ( 7G) EQU R.sup.1 --Ph--CH.sub.2 CH.sub.2 --Ph--CF.dbd.CF--C.tbd.C--Ph--R.sup.2( 7H) EQU R.sup.1 --Ph--OCH.sub.2 --Ph--CF.dbd.CF--C.tbd.C--Ph--R.sup.2( 7I) EQU R.sup.1 --Ph--CH.sub.2 O--Ph--CF.dbd.CF--C.tbd.C--Ph--R.sup.2( 7J) EQU R.sup.1 --Ph--COO--Ph--CF.dbd.CF--C.tbd.C--Ph--R.sup.2 ( 7K) EQU R.sup.1 --Ph--OCO--Ph--CF.dbd.CF--C.tbd.C--Ph--R.sup.2 ( 7L) EQU R.sup.1 --Ph--C.tbd.C--Ph--CF.dbd.CF--C.tbd.C--Ph--R.sup.2 ( 7M) EQU R.sup.1 --Ph--CH.sub.2 CH.sub.2 --Ph--CF.dbd.CF--C.tbd.C--Ph--R.sup.2( 7N) EQU R.sup.1 --Ph--OCH.sub.2 --Ph--CF.dbd.CF--C.tbd.C--Ph--R.sup.2( 7O) EQU R.sup.1 --Ph--CH.sub.2 O--Ph--CF.dbd.CF--C.tbd.C--Ph--R.sup.2( 7P) EQU R.sup.1 --Ph--COO--Ph--CF.dbd.CF--C.tbd.C--Ph--R.sup.2 ( 7Q) EQU R.sup.1 --Ph--OCO--Ph--CF.dbd.CF--C.tbd.C--Ph--R.sup.2 ( 7R) EQU R.sup.1 --Ph--CF.dbd.CF--.tbd.C--Ph--C.tbd.C--Ph--R.sup.2 ( 7S) EQU R.sup.1 --Ph--CF.dbd.CF--C.tbd.C--Ph--CH.sub.2 CH.sub.2 --Ph--R.sup.2( 7T) EQU R.sup.1 --Ph--CF.dbd.CF--C.tbd.C--Ph--OCH.sub.2 --Ph--R.sup.2( 7U) EQU R.sup.1 --Ph--CF.dbd.CF--C.tbd.C--Ph--CH.sub.2 O--Ph--R.sup.2( 7V) EQU R.sup.1 --Ph--CF.dbd.CF--C.tbd.C--Ph--COO--Ph--R.sup.2 ( 7W) EQU R.sup.1 --Ph--CF.dbd.CF--C.tbd.C--Ph--OCO--Ph--R.sup.2 ( 7X)
Further, the following compound may be mentioned as compound having four rings: EQU R.sup.1 --A.sup.1 --A.sup.2 --CF.dbd.CF--C.tbd.C--A.sup.3 --A.sup.4 --R.sup.2 ( 8)
More specifically, the following compounds may be mentioned as the compound of the formula (8): EQU R.sup.1 --Ph--Ph--CF.dbd.CF--C.tbd.C--Ph--Ph--R.sup.2 ( 8A) ##STR11## EQU R.sup.1 --Cy--Cy--CF.dbd.CF--C.tbd.C--Cy--Cy--R.sup.2 ( 8B) EQU R.sup.1 --Ch--Ch--CF.dbd.CF--C.tbd.C--Ch--Ch--R.sup.2 ( 8C) EQU R.sup.1 --Cy--Ph--CF.dbd.CF--C.tbd.C--Ph--Cy--R.sup.2 ( 8D) EQU R.sup.1 --Ch--Ph--CF.dbd.CF--C.tbd.C--Ph--Ch--R.sup.2 ( 8E) EQU R.sup.1 --Ph--Cy--CF.dbd.CF--C.tbd.C--Cy--Ph--R.sup.2 ( 8F) EQU R.sup.1 --Ch--Cy--CF.dbd.CF--C.tbd.C--Cy--Ch--R.sup.2 ( 8G) EQU R.sup.1 --Ph--Ch--CF.dbd.CF--C.tbd.C--Ch--Ph--R.sup.2 ( 8H) EQU R.sup.1 --Cy--Ch--CF.dbd.CF--C.tbd.C--Ch--Cy--R.sup.2 ( 8I) EQU R.sup.1 --Ph--PhF--CF.dbd.CF--C.tbd.C--PhF--Ph--R.sup.2 ( 8J) EQU R.sup.1 --Cy--PhF--CF.dbd.CF--C.tbd.C--PhF--Cy--R.sup.2 ( 8K) EQU R.sup.1 --Ch--PhF--CF.dbd.CF--C.tbd.C--PhF--Ch--R.sup.2 ( 8L) EQU R.sup.1 --Ph--Ph--CF.dbd.CF--C.tbd.C--Cy--Cy--R.sup.2 ( 8M) EQU R.sup.1 --Ph--Ph--CF.dbd.CF--C.tbd.C--Ch--Ch--R.sup.2 ( 8N) EQU R.sup.1 --Cy--Cy--CF.dbd.CF--C.tbd.C--Ch--Ch--R.sup.2 ( 8O) EQU R.sup.1 --Cy--Ph--CF.dbd.CF--C.tbd.C--Cy--Ph--R.sup.2 ( 8P) EQU R.sup.1 --Ch--Ph--CF.dbd.CF--C.tbd.C--Ch--Ph--R.sup.2 ( 8Q) EQU R.sup.1 --Ch--Cy--CF.dbd.CF--C.tbd.C--Ch--Cy--R.sup.2 ( 8R)
Furthermore, the following compounds may be mentioned as compounds having four rings wherein Y.sup.1 and Y.sup.2 between rings are changed to other than a single bond; EQU R.sup.1 --Ph--C.tbd.C--Ph--CF.dbd.CF--C.tbd.C--Ph--Ph--R.sup.2( 9A) EQU R.sup.1 --Ph--CH.sub.2 CH.sub.2 --Ph--CF.dbd.CF--C.tbd.C--Ph--Ph--R.sup.2( 9B) EQU R.sup.1 --Ph--OCH.sub.2 --Ph--CF.dbd.CF--C.tbd.C--Ph--Ph--R.sup.2( 9C) EQU R.sup.1 --Ph--CH.sub.2 O--Ph--CF.dbd.CF--C.tbd.C--Ph--Ph--R.sup.2( 9D) EQU R.sup.1 --Ph--COO--Ph--CF.dbd.CF--C.tbd.C--Ph--Ph--R.sup.2 ( 9E) EQU R.sup.1 --Ph--OCO--Ph--CF.dbd.CF--C.tbd.C--Ph--Ph--R.sup.2 ( 9F) EQU R.sup.1 --Ph--C.tbd.C--Ph--CF.dbd.CF--C.tbd.C--Ph--Cy--R.sup.2( 9G) EQU R.sup.1 --Ph--CH.sub.2 CH.sub.2 --Ph--CF.dbd.CF--C.tbd.C--Ph--Cy--R.sup.2( 9H) EQU R.sup.1 --Ph--OCH.sub.2 --Ph--CF.dbd.CF--C.tbd.C--Ph--Cy--R.sup.2( 9I) EQU R.sup.1 --Ph--CH.sub.2 O--Ph--CF.dbd.CF--C.tbd.C--Ph--Cy--R.sup.2( 9J) EQU R.sup.1 --Ph--COO--Ph--CF.dbd.CF--C.tbd.C--Ph--Cy--R.sup.2 ( 9K) EQU R.sup.1 --Ph--OCO--Ph--CF.dbd.CF--C.tbd.C--Ph--Cy--R.sup.2 ( 9L) EQU R.sup.1 --Ph--C.tbd.C--Ph--CF.dbd.CF--C.tbd.C--Ph--Ch--R.sup.2( 9M) EQU R.sup.1 --Ph--CH.sub.2 CH.sub.2 --Ph--CF.dbd.CF--C.tbd.C--Ph--Ch--R.sup.2( 9N) EQU R.sup.1 --Ph--OCH.sub.2 --Ph--CF.dbd.CF--C.tbd.C--Ph--Ch--R.sup.2( 9O) EQU R.sup.1 --Ph--CH.sub.2 O--Ph--CF.dbd.CF--C.tbd.C--Ph--Ch--R.sup.2( 9P) EQU R.sup.1 --Ph--COO--Ph--CF.dbd.CF--C.tbd.C--Ph--Ch--R.sup.2 ( 9Q) EQU R.sup.1 --Ph--OCO--Ph--CF.dbd.CF--C.tbd.C--Ph--Ch--R.sup.2 ( 9R) EQU R.sup.1 --Ph--Ph--CF.dbd.CF--C.tbd.C--Ph--C.tbd.C--Ph--R.sup.2( 9S) EQU R.sup.1 --Ph--CF.dbd.CF--C.tbd.C--Ph--CH.sub.2 CH.sub.2 --Ph--R.sup.2( 9T) EQU R.sup.1 --Ph--Ph--CF.dbd.CF--C.tbd.C--Ph--OCH.sub.2 --Ph--R.sup.2( 9U) EQU R.sup.1 --Ph--Ph--CF.dbd.CF--C.tbd.C--Ph--CH.sub.2 O--Ph--R.sup.2( 9V) EQU R.sup.1 --Ph--Ph--CF.dbd.CF--C.tbd.C--Ph--COO--Ph--R.sup.2 ( 9W) EQU R.sup.1 --Ph--Ph--CF.dbd.CF--C.tbd.C--Ph--OCO--Ph--R.sup.2 ( 9X)
Further, the following compounds may be mentioned as examples in which some of hydrogen atoms of the 1,4-phenylene group, the trans-1,4-cyclohexylene group and the 1,4-cyclohexenylene group of A.sup.1, A.sup.2, A.sup.3 and A.sup.4 are substituted by halogen atoms or cyano groups, or some of .dbd.CH-- groups constituting a ring are substituted by nitrogen atoms, or some of --CH.sub.2 -- groups constituting a ring are substituted by oxygen atoms or sulfur atoms. ##STR12##
The compound of the formula (1) of the present invention is used in the form of a liquid crystal composition prepared by mixing at least one such compound with other liquid crystal material and/or a non-liquid crystal material, whereby the liquid crystal composition can be made to have a low viscosity, and it is possible to attain a high speed response when the composition is formed into a liquid crystal display device.
The material which may be mixed with the compound of the present invention, includes, for example, the following compounds. In the following formulas, each of R.sup.C and R.sup.D represents an alkyl group, an alkoxy group, halogen atom or a cyano group, provided that "--NON--" represents an azoxy group.
R.sup.c --Cy--Cy--R.sup.D PA1 R.sup.c --Cy--Ph--R.sup.D PA1 R.sup.c --Ph--Ph--R.sup.D PA1 R.sup.c --Cy--COO--Ph--R.sup.D PA1 R.sup.c --Ph--COO--Ph--R.sup.D PA1 R.sup.c --Cy--CH.dbd.CH--Ph--R.sup.D PA1 R.sup.c --Ph--CH.dbd.CH--Ph--R.sup.D PA1 R.sup.c --Cy--CH.sub.2 CH.sub.2 --Ph--R.sup.D PA1 R.sup.c --Ph--CH.sub.2 CH.sub.2 --Ph--R.sup.D PA1 R.sup.c --Ph--N.dbd.N--Ph--R.sup.D PA1 R.sup.c --Ph--NON--Ph--R.sup.D PA1 R.sup.c --Cy--COS--Ph--R.sup.D PA1 R.sup.c --Cy--Ph--Ph--R.sup.D PA1 R.sup.c --Cy--Ph--Ph--Cy--R.sup.D PA1 R.sup.c --Ph--Ph--Ph--R.sup.D PA1 R.sup.c --Cy--COO--Ph--Ph--R.sup.D PA1 R.sup.c --Cy--Ph--COO--Ph--R.sup.D PA1 R.sup.c --Cy--COO--Ph--COO--Ph--R.sup.D PA1 R.sup.c --Ph--COO--Ph--COO--Ph--R.sup.D PA1 R.sup.c --Ph--COO--Ph--OCO--Ph--R.sup.D ##STR13##
These compounds are given merely as examples. The ring structures or hydrogen atoms of the terminal groups may be substituted by halogen atoms, cyano groups or methyl groups, and the cyclohexane rings or the benzene rings may be replaced by other six-membered or five-membered rings such as pyridine rings or dioxane rings. Further, the linking group between the adjacent rings may be changed. Thus, various materials may be approximately selected for use depending upon the desired properties.
The liquid crystal composition containing the compound of the present invention may be injected into a liquid crystal cell, so that it is interposed between substrates provided with electrodes, to constitute a liquid crystal electro-optical device.
A typical liquid crystal cell may be a twisted nematic (TN) type liquid crystal electro-optical device. Here, the term "liquid crystal electro-optical device" is used to express that it is useful not only for application to a display device but also to e.g. a light adjustable window, a light shutter or a polarizing exchanger device.
The liquid crystal electro-optical device can be used in various modes such as a twisted nematic system, a guest-host system, a dynamic scattering system, a phase change system, a DAP system, a double frequency drive system and a ferroelectric liquid crystal display system.
Now, a structure of a liquid crystal electro-optical device and a specific example for the preparation will be described.
On a substrate made of a plastic, glass or the like, an undercoat layer of SiO.sub.2, Al.sub.2 O.sub.3 or the like, or a color filter layer is formed as the case requires, and then an electrode for In.sub.2 O.sub.3 -SnO.sub.2 (ITO), SnO.sub.2 or the like is formed thereon, followed by patterning. Then, an overcoat layer of polyimide, polyamide, SiO.sub.2 or Al.sub.2 O.sub.3 is formed as the case requires, followed by orientation treatment. Then, a sealing material is printed, and the periphery is sealed so that the electrode surfaces face to each other, followed by curing the sealing material to form an empty cell.
To this empty cell, the composition containing the compound of the present invention is injected, and the injection inlet is then sealed with a sealing agent to form a liquid crystal cell. To this liquid crystal cell, a polarizing plate, a color polarizing plate, a light source, a color filter, a semitransparent reflecting plate, a reflecting plate, a photoconducting plate, an ultraviolet ray-preventive filter or the like may be laminated, letters or designs may be printed, and nonglare treatment may be applied as the case requires, to obtain a liquid crystal electro-optical device.
The above description is intended to show merely the basic structure and the basic method for preparation of a liquid crystal electro-optical device. Various other structures may be employed, including, for example, a double layer liquid crystal cell having two liquid crystal layers with a substrate employing double layer electrodes, and an active matrix device using an active matrix substrate having a functional element such as TFT or MIM formed thereon.
By using the compound of the present invention for a liquid crystal composition, high speed response can be expected also by conducting high duty drive. Therefore, the present invention is effectively applicable to a supertwisted (STN) type liquid crystal electro-optical device having a highly twisted angle, to which an attention has been drawn in recent years. Further, the present invention is useful also for a guest-host (GH) type liquid crystal display device using multicolor colorants or a ferroelectric liquid crystal electro-optical device.
The compound of the formula (1) of the present invention can be produced, for example, by the following method. ##STR14##
In the above formulas, each of A.sup.1, A.sup.2, A.sup.3 and A.sup.4, which are independent from one another, is a cyclic group selected from a trans-1,4-cyclohexylene group, a 1,4-cyclohexenylene group and a 1,4-phenylele group. Each of these cyclic groups is unsubstituted or substituted by one or more halogen atoms or cyano groups. One or more .dbd.CH-- groups constituting rings of such cyclic groups may be substituted by nitrogen atoms, and one or more --CH.sub.2 -- groups constituting such rings may be substituted by oxygen atoms or sulfur atoms.
Each of Y.sup.1 and Y.sup.2 which are independent from each other, is --COO--, --OCO--, --C.tbd.C--, --CH.sub.2 CH.sub.2 --, --CH.dbd.CH--, --OCH.sub.2 --, --CH.sub.2 O-- or a single bond.
Each of m and n, which are independent from each other, is 0 or 1.
Each of R.sup.1 and R.sup.2, which are independent from each other, is a C.sub.1-10 alkyl group, a halogen atom or a cyano group. In the case of an alkyl group, an oxygen atom, a carbonyloxy group or an oxycarbonyl group may be interposed in a carbon-carbon bond in this alkyl group or in the carbon-carbon bond between this alkyl group and the cyclic group. Further, some of carbon-carbon bonds in the alkyl group may be triple bonds or double bonds. Furthermore, one --CH.sub.2 -- group in the alkyl group may be substituted by a carbonyl group, and some or all of hydrogen atoms in the alkyl group may be substituted by fluorine atoms.
X is a bromine atom or an iodine atom.
Chlorotrifluoroethylene of the formula (10) is treated with n-butyl lithium and then reacted with chlorotrimethylsilane of the formula (11) to obtain 1,1,2-trifluoro-2-trimethylsilylethylene of the formula (12). Then, without isolation, this compound (12) is reacted further with a lithium compound of the formula (13) to obtain a difluoroethylene compound of the formula (14).
The obtained compound (14) is hydrolyzed with water and potassium fluoride to obtain a difluoroethylene compound of the formula (15). This compound is treated with n-butyl lithium and then reacted with iodine to obtain an iodide compound of the formula (16). Further, an acetylene derivative compound of the formula (17) is reacted thereto in the presence of a palladium catalyst, copper iodide and triethylamine to obtain a difluoro compound of the formula (1).
To introduce an acyl group to R.sup.1 and R.sup.2 of the compound of the formula (1), a compound of the formula (1) wherein R.sup.1 and R.sup.2 are hydrogen atoms and an acyl halide may be subjected to a Friedel-Crafts reaction. To introduce a cyano group, a compound of the formula (1) wherein R.sup.1 and R.sup.2 are bromine atoms or iodine atoms may be reacted with CuCN. Further, to introduce an ethynylene group (--C.tbd.C--) to Y.sup.1 and Y.sup.2 of the compound of the formula (1), a compound of the formula (1) wherein R.sup.1 and R.sup.2 are bromine atoms or iodine atoms and an alkynyl lithium compound may be subjected to a coupling reaction.